Fornia



L. D. MILLS.

FILTER.

APPLICATION FILED JULY [4,1920- .Patented Oct. 31, 1922.

2 SHEETSSHEET l- L.YD. MILLS.

FILTER.

APPLICATION FILED JULY 14, I920.

Patented Oct. 31, 1922.

2 SHEETS-SHEET 2.

Patented Oct. 31, 1922.

UNITED STATES PATENT OFFICE.

LOUIS D. MILLS, OF REDWOOD CITY, CALIFORNIA, ASSIGNOR 10 THE MERRILL COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF CALI- FORNIA.

FILTER.

Application filed July M,

To all w]: 0% it may concern Be it known that I, LOUIS D. MILLs, a citizen of the United States and a resident of Redwood City, in the county of San Mateo and State of. California, have invented certain new and useful Improvements in Filters. of which the following is a specification.

The invention relates to filters, and more particularly to filter presses of the plate and frame type in which a solution carrying .7 lids in suspension is conducted to a filteriug medium upon which the solids are depositelfl and through which solutions are passed.

It is desirable in the operation of this type of filter to secure a uniform and homogeneous layer of the solids over the surface of the filtering medium in order that there may be a uniform and intimate contact between the solutions and the solids as the solutions pass through the solids on the filtering medium With such filter presses as at present constructed, it is impossible to secure the deposition of a homogeneous layer of the solids uniformly over the surface of the filtering medium. In filter presses of the frame and plate type the various sizes of solids tend to segregate so that the contact between the solids and the solutions passing through them is not uniform. Many efforts have been heretofore made to secure a. more homogeneous layer of the solids and a more uniform distribution of them over the filtering medium. but thus far with only partial success. Either the layer is not homogeneous. or it is not uniformly distributed, or it is neither homogeneous nor uniformly distributed. This undesirable condition has been caused by maintaining the filtering medium and the stream of solution carrying the solids in suspension in fixed relative positions so that the action of gravity tends to segregate the solid particles according to their weight. Efforts have been made to counteract this segregation by violently agitating the solution as it enters the containers and comes in contact with the filtering medium. These efforts have proven more or less unsuccessful with the result that at the present time. when the filtering medium. is removed from thepress. it is found that the particles of similar substances have segregated on the 1920. Serial No. 396,057.

filtering medium according to their respective sizes. And in processes dependent upon a uniform and equal contact between solutions and solid particles deposited within such presses this segregation has resulted in. imperfect results.

The object of the present invention is to secure a more homogeneous and more even or uniform deposition or distribution of the solid particles over the surface of the filtering medium, in order that each unit volume of solutions subsequently passed through the filter shall come in cont-act with an equivalent unit area of solid matter, that is to say, there will be a uniform contact between the solutions and the solid particles for the purpose of accomplishing the desired reaction. ll ith this object in view, the invention conu continually changing the relation or relatlve positions between the filtering meium and the streamof solution carrying "l solid particles in suspension. By continuouslv moving the surface of the filterledium with relation to the flow of the stream] of solution and in conjunction with the flow of solution. the force of gravity tends to uniformly distribute the solid particles over the filtering; medium with the re sult that the coarser and finer particles are homogeneously mixed and deposited in a layer uniform in thickness. Therefore all solutions, whether carrying solid matter in suspension or not that pass through the filtering; medium, come into intimate and uniform. contact with all the solid particles. This results in effecting a reduced consumption of the material used or required to form the layer of solid particles on the filtering znedirun. and in a more efficient performance of the chemical reaction desired.

The preferred form of the invention is illustrated in the accompanying drawings in which 1 and 2 are respectively a p an and a: side elevation of a plate and f me filter press embodying; the principles of the invention; Fig. 3 is a side elevation of a frame and Fig. 4- is a side elevation of a late used in a rectangular filter, this be the preferred form of the invention; is a side elevation of a frame and Pig 6 is a side elevation of a plate used in a cylindrical filter; and Fig. 7 is a section taken on the line 7-7 of Fig. 6.

The filter of the invention may be used for causing an intimate contact between solutions passing through a filtering medium and solid particles deposited upon the surface of the filtering: medium for whatever purpose it desired to secure this intimate and uniform contact between solutions and solid particles. The solid particles may be introduced continuously with the stream of solution or the solid particles may be introduced with solution to form a deposit upon the surface of the filtering medium. and then other solutions passed through them. hiioreover, the filter is adapted for use where all or a portion of the solid particles are precipitated from the solutions.

F or the purpose of illustrating the principles of the invention it is assumed that the filter illustrated in the drawings, and particularly described hereinafter. is employed for precipitatins and recovering metals from cyanide solutions. In this method a stream of solution in which the metals have been dissolved carries the solid particles of precipitant in suspension. The solid particles of precipitant are deposited over the surface of the lilteing medium. Then as the solution of the dissolved metals passes through the particles of precipitant the metals in solution are precipitated by the particles of precipitant on tie surface of the filtering med um. Although the filter illustrated in the drawings described as em ployed for this purpose. it will be understood that the invention is to be bv no means restricted to this use inasmuch as it is obvious that it is applicable to any filtering action in which a stream of solution is passed through a filteringmedium upon the surface of which solid particles are distributed in contact with which it is desired to lnringythe solution. whether or not the lution ca rr'ies the solid particles continuousy with it or the tires; volume of the solution .epos tsthem and the subsequent solution is ree :ronii the solid particles.

The iilter illustrated in the drswin consists of a number of plates and frames which when clumped loge form a series of A l chznnbers interconnected by means of inlet and outlet solution channels. In 3 is shown an elevation of one of the frames, and in n 4t is Sl10\ 7D an. elevation of one of the plates. Each frame 53 preferably square in form and provided with ears or supporting lugs (3 so as to support the frames on the side bars during; the assembling of the complete filter. The plates 8 are s milarly provided with ears or lugs 9 for the same purpose. The front end of the filter is provided with a heed ll and the opposite end is n'ovided with rear head 12. Interposed between the last frame and plate unit and the rear head is a follower 13 against which bear the ends of tightening; screws til threaded in the rear head. In its messes in lu'aclzets 22 supported by the c ndard 16. l he other end of the shaft 21 ca rries a worm gear 2% which driven by a worm 25 mounted on a shaft 26 journaled in the brackets 27 extending; from the standard 16. The shaft is driven from any convenient source of power. means of the alxve described construction an desired speed of rotaion may be imported to the filter. Q he speed of rotation will. vary somewhat llCCi .ing; to the character of wort: being performed in the filter, but for general preci i a and other purpo. es it will be founc that a soeco L l of one revolution 21 minute is satisfactory.

The solution undergoing treatment is led in o the filter throu f 'eed gipe and the barren solution is conducted from the filter through the discharge pipe 30. In order tl the filter .Hlfff remain full of solution at all times, even when the ii w is interrupted, the inlet and outlet orifice: of the pipes and 30 are preferably on a level. higher than the top of the filter. The trunnion 32 of the is provided. with a central core inlet or feed pipe 29 enters the Pi nironirh a box 342 so that there may be n leakage of the solution between the moving end ofthe trunnion 32 and the stationary end of the feed pipe 29. The core vminetes in a conduit arranged radially in tile head ll, said conduit terminzz't' .it the inner face of the head near the m-iphei thereof. The plates and frames 11'0 provi .ed at one corner witl'i holes 36 vhich all register with each other and with "he discharge or .1; of the conduit in be head 11 so t the holes 36 constitute a $1 tnroiurhont the length of holes 36 discharge into the of the frames througrh the pipes 38.

ne th of the pipes 38 will depend upon or t 1e so ution unfero' I i l oing; treatconditions of operation. Iz

38 discharge the solution (.2111 Vll"r{ 1 the particles of solid meter in susision at substantially the middle of the .s. The solution passes from the inof each frame through the filtering diuin 37 with Which each of the olwres (l is covered, leaving the solid particles deposited upon the surface of the filterin )3 medium. The barren or filtered solution is discharged from the filter through a series of aligned holes i0 formed in a corner of the plates and frames. The holes regletter with the conduit 42 cored in the follower 13. it the point at which the cored hole in the follower 13 connects with the forward end 43 of the discharge pipe 30 the follower 13 is provided with a stufling box to prevent leakage.

The filter operates as follows: The solution carrying; the particles of solid matter in suspension discharges into the interior of the frames 5 by way of the pipes 38. As the whole filter slowly revolves on its trunnions it will be seen that the direction of flow of the stream of solution is constantly and continually chai'iging with respect to the surface of the filtering medium. Moreover, inasmuch as the filtering: media themselves are rotating with the pipes 38 they also change their positions relatively to the flow of the stream of solution. having; both the stream of solution and the filtering medium change their relative positions, substantially i'iniform distrilmticn of the particles'of solid. matter is secured. By causing the filtering mednnn to move and shift its position relatively to the stream of solution, the particles of solid matter are prevented from building; up on the filtering metium in zones composed of particles of one size. It will be understood that as the filter slowly rotates, the direction of the How of solution from the pipes 38 constantly ciangzes. At one point in its period of rotation it is pointing: up-

ard. at another obliquely, at another horizontally, and another downwardly. At the same time the filteringmedium is r0tatinn so that the heavier particles of the solid matter which c nstantlv tend to fall faster and farther than the lighter particles under the action of nravi v. have no opportuuitv to build up in zones on any particular point of the surface of the filtering medium.

but fall in a more or less uniform screen or curtain GYPIllY distributed over substantially the whole of the filtering; surface. For the same reason that the larger particles of solid matter are evenly distributed over the filtering surface. the smaller particles are evenly distributed. Thus there is secured an intimate and homogeneous mixture of the larger and smaller particl s. The same action which causes the larger and su'iallei." particles to be mixed in a homogeneous manner causes the mixture to be deposited in a layer of substantially uniform thickness.

The mode of operation of the filter illustratcd in conjunction with the precipitation of cyanide solutions bv means of powdered piecipitants such as incl} divided zinc is as follows :The solution carrying the powdered zinc precipitant in suspension passes into the filter through the feed pipe 29 and is discharged into the interior of the frames 5 through the pipes 38. The zinc particles distribute themselves over the surfaces of the filtering media. As the solution passes through the layer of zinc 0n the surface of the filtering media the metals held in solution are precipitated out onto the particles of zinc and the barren solution linds its way out through the holes 40 and the discharge pipe 30. The solution continues to flow through the filter until there is built up upon the surfaces of the filtering; media a compact layer of precipitant and precipitated metal. .sit stated intervals the operation of the filter is discontinued and the filter is opened for the removal of the accumulated cake of precipitate.

In case a cylindrical form of filter is em ployed, the frames and plates will have the construction shown in 5 and 6 respec tively. The principle of construction of these parts is substantially the same as that of the parts shown in Finis. 3 and 4 except that thev are round instead of square. They are provided with lugs 4t? bv which they are supported in position when the filter is assembled. The solution carrying the solid particles in suspension enters the frame l8 through the conduit hole 49 and discharges into the middle of the frame through the pipe 50. The solution passes through the tilterinszmediiun with which the plate 51 is covered and passes out through the dis charge conduit The mode of operation of this form of the invention is precisely as the mode of operation of the preferred form of the invention.

Having thus pointed out the principles of the invention and illustrated and described one embodiment thereof, it being understood hat the invention may otherwise be embodied, what I claim as new is l. A filter comprising a series of filtering: frames and plates, a filtering medium on the surfa -e of each plate, an nlet conduit passing through the plates and frames and discharging into the interior of each frame, an outlet conduit passing through the plates and frames and receiving the filtered solution from the interior of each plate, and means fo rotating the filter.

2. A filter comprising a series of vertirally arranged filtering frames and plates, a filtering medium on the surface of each plate, means for conducting a stream of solution carrvinn solids in suspension into the interior of each frame, and means for causing, the solids to be deposited out of the so lution in a homogeneous and uniform layer over the filtering media.

A filter comprising a series of vertically arranged filtering frames and plates, a filterinnmedium covering each face of the plates, means for conducting a stream of solution carrying solids in suspension into the interior of the frames, and means for moving the filter so that the solids will die posit out of the solution in a homogeneous layer oi uniform thickness on the filtering media.

at. A iilter comprising a series of vertically arranged filtering frames and plates, a filtering; medium covering each face of the plates, means for rotatably supporting the filter. and means for rotating the filtel.

A tilt-er comprising a series of vertieall arranged filtering frames and plates, a filtering; medium covering each face of the plates heads arranged at the ends of the plates and frames, trunnions formed on the heads for rotatahly supporting the filter,

means for introducing the solution to be filtered into the frames through one trunnion, and means for conducting the filtered solution out through the other trunnion.

6. A plate and frame filter having filtering media covering the faces of the plates, means for conducting a solution containing solids in suspension to the filtering media so that the solids will be deposited upon the filtering media and means for revolving the filter so that there will be an intimate and uniform Contact between the solution and the solids deposited on the lil tering media.

LOUIS D. MILLS. 

